Implantable electronic devices are in use providing electronic pulses to stimulate tissue via a lead extending from an implanted pulse generator to a desired internal location. An example of this type of technology is a pacemaker and a pacing lead which provides electrical stimulation to the heart. The pacemaker is usually implanted in a subcutaneous cavity, and the leads extend either transvenously to the internal cavities of the heart, or to patch electrodes located on external surface of the heart.
The leads generally include at least one, and often two or more, electrodes located at a distal end, and a connector having a similar number of electrical connector elements for interconnection to the pulse generator at the proximal end. The electrical connector elements, or contacts, at the proximal end and the distal electrodes are interconnected by conductors extending through an insulated lead body. It is common for the leads to include helically wound conductors which are either coaxially mounted or side-by-side wound within the lead body, separated by insulation.
The connector is inserted into a receiving orifice in a header portion of the pulse generator. The header portion of the pulse generator may be formed from an epoxy material which is assembled and bonded to the main body of the pulse generator. The main body of the pulse generator is generally a metallic self-contained housing or can, which encloses the source of electrical energy and electrical circuitry for controlling the electrical stimulus delivered by the lead.
In the design of the lead connector and the pulse generator, it is important for the lead to be safely secured to the pulse generator to prevent inadvertent decoupling. Generally, connectors have been assembled using flexible insulation materials to separate the respective electrical components. Problems which arise in the construction and use of multiple conductor lead connectors are primarily related to the design of the electrical interconnection between the conductors and the contacts. The connector must be constructed in a manner which prevents fluids from invading the connector and shorting the electrical conductors therein.
The strength of the existing IS-1 connector widely used in the current generation of passive fixation pacing leads is adequate for a normal usage condition. However, when the connector is adversely misused, the connector pin may be separated away from the connector. For example, an attempt to withdraw the connector pin from the pacer header while a setscrew commonly used to firmly affix it to the header is inadvertently forgotten to be unfastened, may result in a connector pin to connector separation. The connector design of the invention serves to strengthen this potentially weak region, thereby minimizing the problem. Also, the locking mechanism simplifies the assembly process as well as making it more repeatable. Currently, the parts have freedom to move during and after the bonding process. With the design of the invention, however, the parts are locked in place and are unable to move relative to each other during subsequent bonding operations.
A number of patents are representative of the prior art in this regard.
U.S. Pat. No. 5,807,144 to Sivard discloses a device for affixing an elongate contact pin on an electrode lead for connection to a medical implant containing an elongate connector part with an opening at one end into which the contact pin can be inserted. The connector part has an affixing part which, when acted on by the contact pin, can move in the connector part's longitudinal direction between a contact pin-affixing position and a contact pin-release position.
U.S. Pat. No. 5,782,900 to de la Rama et al. discloses safety anchoring pins on a tip electrode to match receptacle holes on a catheter shaft and/or the extended flexible stem on the tip electrode maintains the integrity of the catheter system from potential complications of undesired components disengagement.
U.S. Pat. Nos. 5,531,781 to Alferness et al. and 5,383,922 to Zipes et al., disclose a connection means of the pin and groove type but do not specifically spell out the connection. U.S. Pat. No. 5,514,172 to Mueller discloses a ring connector with deflectable circular elements which engage with holes in a rigid insulator to produce a connection for a multi-conductor lead device.
U.S. Pat. Nos. 3,397,377 to Potter; 2,947,966 to Francis et al.; and 1,021,195 to Knauff all disclose circular connector bodies outside of the field of the invention and having bayonet type slots for engagement by pins or the like.
It was with knowledge of the foregoing state of the technology that the present invention has been conceived and is now reduced to practice.